The present disclosure relates to semiconductor processing equipment, and in particular to monitoring unit for monitoring the operation of a plasma treatment apparatus.
Semiconductor fabrication processes include deposition processes for forming thin films on a semiconductor wafer (hereinafter, referred to as a “substrate”), etching processes for selectively removing material from the substrate, and the like. Many semiconductor fabrication processes involve a treatment using plasma. A semiconductor fabrication process using a plasma is referred to herein as a “plasma treatment process,” and can include a plasma deposition process, a plasma etching process, a plasma cleaning process, and the like. The use of a plasma treatment process may decrease the amount of time needed to perform a semiconductor fabricating process, and/or may allow the process to be more easily controlled, so that it may be possible to perform a more precise operation.
In a plasma etching process, the plasma is used to selectively remove a thin film from a substrate. The plasma is created by supplying a reaction gas into a chamber in which the substrate is placed, and applying radio frequency (RF) electromagnetic energy to the reaction gas to generate the plasma. The RF energy is applied to an upper and lower electrode that are disposed within the chamber. In order to improve treatment efficiency, a ring-shaped insulating member may be disposed around the upper electrode and/or the lower electrode, and plasma is formed above an upper portion of the substrate. The ring-shaped insulating member is typically formed from quartz.
During a plasma process, some components of the etching apparatus are exposed to the plasma within the chamber. In particular, the ring-shaped insulating members are exposed to the plasma during the plasma process. The plasma, which has a high energy, can cause exposed components within the chamber to erode. In particular, quartz components within the chamber are susceptible to erosion. When the quartz ring-shaped insulating members erode, process conditions within the chamber can change. Thus, it is generally advisable to replace the ring-shaped insulating members from time to time before they erode to the point that a process defect is generated.
If a plasma process, such as a plasma etching process, is not terminated at an appropriate time, the quality of the device that is being fabricated may be degraded. Moreover, particles from the eroded component of the apparatus may contaminate the device. An etching defect may be generated due to a difference in a process condition, such as temperature, etching speed, and the like. When a ring-shaped insulating member erodes, process conditions may vary across the surface of the substrate. Thus, for example, an edge portion of the substrate may have a higher risk of being damaged than a center of the substrate.
In general, an etching process may be monitored using optical emission spectroscopy (OES). OES is a method that detects a change in an optical characteristic of the plasma. OES has a problem, however, in that the sensitivity of OES may degrade over time, and/or it may be difficult to spatially monitor a plasma process using OES.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.